This section is intended to provide a background or context to the invention that is recited in the claims. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, what is described in this section is not prior art to the description and claims in this application and is not admitted to be prior art by inclusion in this section.
Antenna design and layout in mobile radio devices, particularly handheld radio devices, has become quite challenging as consumers expect a greater number of radios in a single device to support one or more cellular access technologies, wireless local area networking, global positioning systems and the like. Closely packed electronics are subject to interference with one another, and if antennas are not properly laid out and isolated from one another, the antenna efficiency of one or more antenna can be impacted. But the increasing number of antennas in handheld devices leaves fewer options for the overall layout.
To this end there have been recent attempts to utilize a conductive strip about the exterior of the handset housing to improve antenna performance. But external conductive elements are subject to interference by the user's hand, which in a worst case scenario can de-tune the overall antenna structure so that the antenna goes off frequency, causing an ongoing call to drop.
Using some or all of a mobile device's external housing as an antenna radiator requires there to be one or more non-conductive slots to be formed in the conductive housing to create the radiating element. One slot may provide one end of the radiator where the radio frequency feed line may be placed. The other end of the radiator may be left open due to a second slot or that end may be grounded so as to provide a single-ended loop antenna, with or without a second slot. However, a slot at one end of the radiator can be bridged by the user's hand and detune the antenna causing a dropped call.
Embodiments of these teachings improve upon such external antenna elements.